The H I Lyα (1215.67Å) emission line dominates the far-UV spectra of M dwarf stars, but strong absorption from neutral hydrogen in the interstellar medium makes observing Lyα challenging even for the closest stars. As part of the Far-Ultraviolet M-dwarf Evolution Survey (FUMES), the Hubble Space Telescope has observed 10 early-to-mid M dwarfs with ages ranging from ∼24 Myr to several Gyrs to evaluate how the incident UV radiation evolves through the lifetime of exoplanetary systems. We reconstruct the intrinsic Lyα profiles from STIS G140L and E140M spectra and achieve reconstructed fluxes with 1-σ uncertainties ranging from 5% to a factor of two for the low resolution spectra (G140L) and 3-20% for the high resolution spectra (E140M). We observe broad, 500-1000 km s −1 wings of the Lyα line profile, and analyze how the line width depends on stellar properties. We find that stellar effective temperature and surface gravity are the dominant factors influencing the line width with little impact from the star's magnetic activity level, and that the surface flux density of the Lyα wings may be used to estimate the chromospheric electron density. The Lyα reconstructions on the G140L spectra are the first attempted on λ/∆λ ∼1000 data. We find that the reconstruction precision is not correlated with SNR of the observation, rather, it depends on the intrinsic broadness of the stellar Lyα line. Young, low-gravity stars have the broadest lines and therefore provide more information at low spectral resolution to the fit to break degeneracies among model parameters.

Calcium network diameters are shown to be smaller by 5 % at solar maximum than at minimum. The average cell size at minimum is 22 115 + 99 km. The average size at solar maximum is 20 920 • 112 km, though individual maxima perform differently from each other depending probably on the dispersed remnant magnetic fields. The change in size of the network is interpreted in terms of changes in the size of the supergranular convective cell.

Closely spaced microphotometer tracings parallel to the dispersion of one excellent frame of a K-line time sequence have been utilized for a study of the nature of the K2v, K2R intensities in the case of the solar chromosphere. The frequency of occurrence of the categories of intensity ratio 1K~v/I~R are as follows: 1~2v > IJ~R = 45.3 per cent; l~v = I~R = 4.7 per cent; Ix~v < 1K~R --25 per cent; IK~R=0=22.3 per cent; I~v=0--0.7 per cent. Two types of absorbing components are postulated to explain the pattern of observed K2v, K2R intensity ratios. One component with minor Doppler displacements acting on the normal Kz32 profile, where Ksv > KsR, produces the cases Ksv>> KsR, Ksv = K2R, K2v < KsR. The other component arises from 'dark condensations' which are of size 3500 kms as seen in Ksn. They have principally large down flowing velocities in the range 5-8 km/sec and are seen on Kz spectroheliograms with sizes of about 5000 kms, within the coarse network of emission. These 'dark condensations' give rise to the situation Ksn = 0.Ks-line widths are measured for all tracings where K2v, K2R are measurable simultaneously. The distribution curve of these widths is extremely sharp. The K2 emission source is identified with the bright fine mottles visible on the surface. Evidence for this interpretation comes from the study of auto-correlation functions of K2 intensity variations and the spacing between the bright fine mottles from both spectrograms and speetroheliograms. The life time of the fine mottling is 200 sec.The supergranular boundaries which constitute the coarse network come in two intensity classes. A low intensity network has the fine mottles as its principal contributor to the K emission. When the network is bright, the enhancement is caused by increased K emission due to the accumulation of magnetic fields at the supergranule boundary. The Ks widths of the low intensity supergranular boundary agree with the value found for the bright mottles. Those for the brighter network are lower than this value, similar to the Kz widths as seen in the active regions.It is concluded that bright fine mottling is responsible for the relation, found by Wilson and Bappu, between K emission line widths and absolute magnitudes of the stars.The paper discusses the solar cycle equivalents that stellar chromospheres can demonstrate and indicates a possible line of approach for successful detection of cyclic activity in stellar chromospheres.The last decade has witnessed much interest in the chromospheres of stars, especially on problems regarding the physical parameters that characterize them. There is also the added charm of speculating on the detection of cyclic effects in stellar chromospheres, similar to that which we are aware of in the solar case. The discovery that the widths of the K emission reversals are related to the absolute magnitudes of the stars (Wilson and Bappu, 1957;Bappu, 1954;Wilson, 1954) and that the intensities have an age dependence (Wilson, 1963), together with the high resolution spectroscopic efforts...

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The meeting brought together the majority of General Assembly participants and was a sad farewell to a highly respected and admired scientist, a brilliant organisor and a beloved friend. The texts of the speeches, which were also printed in the General Assembly Newspaper, "Astrocosmos", on 24 August, are reproduced below. PROFESSOR E.K. KHARADZE-ON BEHALF OF THE IAU Dear Colleagues, Friends, Ladies and Gentlemen, On behalf of the International Astronomical Union I express the most profound sorrow caused by the most untimely death of the current President of our Union, the distinguished scientist Professor Manali Kallat Vainu Bappu, 55 years of age. We have all gathered here today at this mournful moment to pay a worthy tribute to his memory. During Professor Bappu's triennial Presidency of our Union, we have witnessed his devotion to the interests of the Union, his very fruitful activity aimed at its consolidation and strengthening of its scientific effectiveness for the further development of our science-astronomy, all over the planet. The members of our Union will also remember Professor Bappu's contribution at the earlier time of his office in the Union as Vice-President in 1967-1973. Professor Bappu's prominent activity in the Union and in the worldwide astronomical community in general carries the features not only of the skill of an experienced eminent scientist, but also of personal tact, kindness and benevolence to everybody, that has always been so highly appreciated by his colleagues and that has made collaboration with him so pleasant and easy.

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